Well, changed my mind and went down to the parts store tonight. They had two FL-500s; one old and one new. I bought both. Not only the louvers look good, there are significantly more louvers than holes in comparision. Plus they appear to be arranged to create a vortex type of flow. As long as the flaps are not poorly formed, I'd be willing to bet you get better flow with this new design.
I can't get a good pic with my phone, but the rest of the filter (on the surface) looks exactly the same. Still made in the USA. I might get that oil can cutter early and break into one to see how it looks...